The deployment in the body of medications and other substances, such as materials useful in tracking biological processes through non-invasive imaging techniques, is an often repeated and advantageous procedure performed during the practice of modem medicine. Such substances may be deployed in either case through non-invasive procedures such as endoscopy and vascular catheterization, as well as through more invasive procedures that require larger incisions into the body of a patient. The non-invasive and less-invasive procedures are generally used when the target area is accessible through a lumen of the body, while the more invasive procedures may be employed when the target area is located deep within the body or otherwise not readily accessible through a lumen of the body.
Previously, during performance of procedures such as endocardial injection or infusion, angioplasty, or biopsy of tissue or fluids, minimally-invasive medical instruments have primarily been steered by physicians to the location within the patient's body at which the procedure was to be performed, using, for example, images from optical devices located at the end of the instruments' lumens or from non-invasive imaging techniques (e.g., x-ray imaging). Once placed at the desired site, the device at the distal end of the instrument would be actuated by the physician to perform the procedure (e.g., injection or infusion, balloon inflation, sample collection). Ideally, the medical device would be actuated precisely at the desired target site, such as in FIG. 1, which illustrates the ideal situation in which a prior art infusion device 1 affixed to lumen 2 is ideally positioned within a blood vessel 3 such that a therapeutic substance 4 is infused directly to the target cells.
In practical applications, however, placement of the distal end of the medical instrument at the desired location within the patient's body requires careful, time-consuming monitoring of the placement of the instrument tip within the body. Even with such care, however, limitations on the quality of the available images and obstruction of views by surrounding tissues or fluids can degrade the accuracy of placement of the instrument. Such difficulties can result in less than optimal injection, infusion, inflation or sample collection.
Moreover, even if positioned properly, the instrument might be aligned with areas in which performance of the medical procedure would not be desired, such as where an asymmetric plaque deposit inside a blood vessel would render infusion delivery or angioplasty ineffective or potentially dangerous. An example of such a situation is illustrated in FIG. 2. FIG. 2 is a side view of an angioplasty balloon 5 of a type well known in the art affixed to lumen 6, positioned within a blood vessel 7 in a location where the medical device has encountered non-uniform conditions. On one side 8 of the blood vessel, the target of the therapeutic substance to be delivered by balloon 5, the endothelial cells line the vessel wall, are in contact with balloon 5 and the desired infusion of the therapeutic substances may proceed. Attached to the other side 9 of blood vessel 7, however, is a common eccentric lesion 10, here shown attached to the vessel and in contact with balloon 5. Due to the presence of lesion 10, the therapeutic substance is blocked from reaching the wall of blood vessel 7, rendering this minimally-invasive surgical procedure ineffective in the region of the lesion.
In view of the problems of the prior art with manual placement and actuation of medical devices during minimally-invasive surgical procedures, there exists a need for an apparatus and method for achieving intelligent, highly precise actuation of minimally-invasive medical devices at target locations within a patient's body.